I know that the PBS feed for small cities that do not have a local affiliate is only available in SD (a shame). Is it at least 16X9 letterboxed in the center of the screen, or is it 4X3 with the sides chopped off or (worst case) stretched?
I have national PBS in the Beaumont ,Tx dma and we have letterbox and side bars ,giving us a postage stamp effect under normal mode. I use partial zoom giving me at least a 16 x 9 letterbox effect.
I'm Grandfathered for the National PBS and it has some programming my local(s) PBS does not. I also use it if I miss a program on local because it isn't always shown again soon. As MikeD-C05 said I use partial zoom.